Solar cells may be defined as devices to convert light energy into electrical energy by using photovoltaic effect of generating electrons when light is incident onto a P-N junction diode. The solar cell may be classified into a silicon solar cell, a compound semiconductor solar cell mainly including a group I-III-VI compound or a group III-V compound, a dye-sensitized solar cell, and an organic solar cell according to materials constituting the junction diode.
A solar cell made from CIGS (CuInGaSe), which is one of group I-III-VI Chal-copyrite-based compound semiconductors, represents superior light absorption, higher photoelectric conversion efficiency with a thin thickness, and superior electro-optic stability, so the CIGS solar cell is spotlighted as a substitute for a conventional silicon solar cell.
Referring to FIG. 1, a CIGS thin film solar cell is generally fabricated by sequentially forming a support substrate 10 including sodium, a back electrode layer 20, a light absorbing layer 30, a buffer layer 40, a high-resistance buffer layer 50, and a front electrode layer 60.
Different from a bulk solar cell, the CIGS thin film solar cell includes a plurality of unit cells, which are connected with each other in series or parallel through patterning processes (P1 to P3). Gaps G1 and G2 are formed while the P1 process and the P3 process are being performed, so that a non-active area (NAA), which is not contributed to the photoelectric output of the solar cell module, is generated. The non-active area (NAA) leads to a power loss in the range of about 5% to about 10% based on the whole output power of the solar cell module.